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Biomedical subjects

S H Rahimtoola

Publications and source records attributed to S H Rahimtoola.

At least 37 records · Page 2Linked to original sources
PubMed1996

Hibernating myocardium has reduced blood flow at rest that increases with low-dose dobutamine.

The study of Sun and coworkers is important because (1) it provides additional data that HM has an inotropic and an attenuated coronary vasodilator reserve. They also provided data that support the conclusion that with dobutamine, the improvement of abnormal LV wall motion is real in many patients. (2) It emphasizes the possibility of a deleterious effect (infarction) of dobutamine in HM and thus the need for appropriate caution during its use. (3) It provides additional data that confirm that areas of perfusion-metabolism mismatch on PET imaging (HM) are associated with a reduced MBF at rest. However, their conclusions about areas of LV dysfunction with "normal" MBF in coronary artery disease are problematic; therefore, one must be extremely cautious about these conclusions on the basis of the data that are presented.

Coronary Circulation↗
PubMed1996

Clinical aspects of hibernating myocardium.

Hibernating myocardium is a condition that is characterized by persistently impaired myocardial and left ventricular function at rest resulting from reduced myocardial blood flow. It is a result of adaptation or from downregulation. It may occur in unstable and chronic stable angina, acute myocardial infarction, and LV dysfunction and congestive heart failure. Recovery of the hibernating myocardium has clearly been shown to occur by successful revascularization either by coronary bypass surgery or by percutaneous catheter techniques.

Humans↗
PubMed1995

From coronary artery disease to heart failure: role of the hibernating myocardium.

Hibernating myocardium is defined as persistently impaired myocardial and left ventricular (LV) function at rest resulting from reduced myocardial blood flow. It may occur in unstable angina and chronic stable angina, acute myocardial infarction, and LV dysfunction and congestive heart failure. Recovery of the hibernating myocardium has clearly been shown to occur with the establishment of successful revascularization either by coronary bypass surgery or by percutaneous transluminal coronary angioplasty. It may be possible to show recovery of the viable myocardium by reducing myocardial oxygen demand and/or by increasing coronary blood flow with pharmaceutical agents.

Chronic Disease↗
PubMed1995

Morphological characteristics of the regurgitant rheumatic mitral valve.

Reparative surgery for valvular insufficiency is attempted frequently. The success of surgery depends partly on the underlying etiology. To establish the morphological characteristics of rheumatic mitral valve disease (insufficiency) (n = 12), mitral insufficiency due to infective endocarditis (n = 12), mitral insufficiency postinfarction (n = 6), rheumatic (predominant) mitral insufficiency postinfarction (n = 6), rheumatic (predominant) mitral stenosis (n = 12) and normal patients (n = 12) were examined retrospectively. In the groups of patients with mitral insufficiency< the mobility of the posterior leaflet tip (change in angle from the annular plane) was significantly less than normal 48 +/- 9 degrees only in the rheumatic group (12 +/- 7 degrees, P < 0.01). The posterior mitral leaflet tip had greater than normal mobility in the other mitral insufficiency groups: infective endocarditis 53 +/- 15 degrees (P = 0.35 versus normals), postinfarction 63 +/- 11 degrees (P = 0.02 versus normals), myxomatous 63 +/- 19 degrees (P = 0.03 versus normals). The mobility of the posterior mitral leaflet tip was also significantly less than normal in the rheumatic mitral stenosis group: 16 +/- 7 degrees, P < 0.01 versus normals. In the two rheumatic groups, diastolic doming of the anterior mitral leaflet was seen solely in mitral stenosis. In the predominant regurgitant group, the tip of the anterior mitral leaflet was much more mobile than in the stenosis group. Doming of the anterior mitral leaflet was absent from the predominant regurgitant group (2.1 +/- 0.9 cm, P < 0.001). The stenotic mitral valves domed 0.75 +/- 0.15 cm.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography, Doppler, Color↗
PubMed1994

Nifedipine in asymptomatic patients with severe aortic regurgitation and normal left ventricular function.

BACKGROUND: Vasodilator therapy with nifedipine reduces left ventricular volume and mass and increases the ejection fraction in asymptomatic patients with severe aortic regurgitation. METHODS: To assess whether vasodilator therapy reduces or delays the need for valve replacement, we randomly assigned 143 asymptomatic patients with isolated, severe aortic regurgitation and normal left ventricular systolic function to receive either nifedipine (20 mg twice daily, 69 patients) or digoxin (0.25 mg daily, 74 patients). RESULTS: By actuarial analysis, we determined that after six years a mean (+/- SD) of 34 +/- 6 percent of the patients in the digoxin group had undergone valve replacement, as compared with only 15 +/- 3 percent of those in the nifedipine group (P < 0.001). In the digoxin group, valve replacement (in a total of 20 patients) was performed because of left ventricular dysfunction (ejection fraction < 50 percent) in 75 percent, left ventricular dysfunction plus symptoms in 10 percent, and symptoms alone in 15 percent. In the nifedipine group, all six patients who underwent valve replacement did so because of the development of left ventricular dysfunction. In addition, all the patients in both groups who underwent aortic-valve replacement had an increase of 15 percent or more in the left ventricular end-diastolic volume index. After aortic-valve replacement, 12 of the 16 patients (75 percent) in the digoxin group and all six patients in the nifedipine group who had had an abnormal left ventricular ejection fraction before surgery had a normal ejection fraction. CONCLUSIONS: Long-term vasodilator therapy with nifedipine reduces or delays the need for aortic-valve replacement in asymptomatic patients with severe aortic regurgitation and normal left ventricular systolic function.

Adult↗
PubMed1994

Transthoracic and transesophageal echocardiography pre and post percutaneous mitral catheter balloon valvulotomy.

Catheter balloon valvulotomy (CBV) is useful in the relief of rheumatic mitral stenosis. Morphologic scoring of the mitral valve by transthoracic echocardiography is predictive of success with CBV. Horizontal plane transesophageal echocardiography can obtain high quality images of the mitral valve and left atrium, but its value with routine use in the pre and post CBV setting is unknown. We prospectively examined 14 patients with mitral stenosis, pre and post CBV, noting scores, complications of mitral stenosis, and complications of CBV. Mitral valve scoring was similar by TTE and TEE pre and post CBV, but TEE did tend to underestimate scores pre CBV. There was a single thrombus, it was detected only by TEE. Post CBV, both TTE and TEE detected one of two torn chordae. Of three patients with ASD's by colour flow mapping, TTE and TEE each detected two. Increases in mitral insufficiency post CBV were seen equally frequently by TTE and TEE. The increases appeared to be of a higher grade (NS) by TEE. TTE and TEE yielded complementary findings, pre and post CBV. Other than for the detection of thrombi through, the net clinical contribution of routine use of TEE appears small, and large series would be needed to establish its contribution.

Cardiac Catheterization↗
PubMed1993

Survival 15 to 20 years after coronary bypass surgery for angina.

OBJECTIVES: The aim of this study was to determine the 15- to 20-year outcome of coronary bypass surgery in patients with angina. BACKGROUND: Coronary bypass surgery has been performed for > 20 years; we need to know the expected outcome of a very long-term follow-up. METHODS: Using actuarial techniques, we determined the outcome of coronary bypass surgery performed for chronic stable and unstable angina in 7,529 patients from 1969 to 1988. RESULTS: The 5-, 10-, 15- and 20-year survival rates (mean +/- SE) were 88 +/- 1, 73 +/- 1, 53 +/- 1 and 38 +/- 3%, respectively, for the whole group. Compared with patients operated on in 1974 to 1988 (n = 7,026), patients operated on in 1969 to 1973 (n = 503) were younger and had less coronary artery disease but had a higher operative mortality rate and a shorter long-term survival time; 15- and 20-year survival of the 1969 to 1973 cohort was 47 +/- 2% and 33 +/- 3%, respectively. The 1974 to 1988 cohort of patients had a 2.1% operative mortality rate and a 10- and 15-year survival probability of 74 +/- 1% and 55 +/- 2%, respectively. For 2,128 patients with "normal" left ventricular function, the 10- and 15-year survival probability was 82 +/- 1% and 64 +/- 3%, respectively, and for 2,413 patients with "abnormal" left ventricular function, it was 66 +/- 1% and 47 +/- 3%, respectively (p < 0.0001); for men it was 74 +/- 1% and 56 +/- 2%, respectively, and for women, 70 +/- 2% and 52 +/- 5%, respectively, p < 0.05. The actuarial percentages of reoperation and myocardial infarction at 15 years were 33 +/- 2% and 26 +/- 2%, respectively; these values did not differ significantly between men and women. There was a significant (p < 0.001) difference between men and women in angina status; 81% of the men versus 74% of the women had no angina or mild angina at the most recent follow-up study. CONCLUSIONS: Coronary bypass surgery is an effective form of therapy for angina (for 15 to 20 years) in both men and women.

Age Factors↗
PubMed1993

The hibernating myocardium in ischaemia and congestive heart failure.

Hibernating myocardium refers to the presence of persistent myocardial and left ventricular dysfunction at rest due to reduced coronary blood flow that can be partially or completely restored to normal by myocardial revascularization. An increasing amount of data show it is most likely a downgrading of cardiac function so that blood flow and myocardial function are once again in a state of equilibrium. It has been demonstrated to occur in patients with unstable angina, chronic stable angina, acute myocardial infarction and in left ventricular dysfunction and/or congestive heart failure. Salvage of this viable myocardium by successful revascularization improves left ventricular dysfunction and probably also patient survival. Therefore, diagnosis of hibernating myocardium is important because it does not render left ventricular dysfunction a necessary contraindication to revascularization, nor does it leave the patient with chronic heart failure a candidate only for cardiac transplantation. Instead, these patients should have complete revascularization by coronary bypass surgery/percutaneous transluminal coronary angioplasty as soon as possible.

Angina Pectoris↗
PubMed1993

Survival at 15 to 18 years after coronary bypass surgery for angina in women.

BACKGROUND: Coronary bypass surgery in women is associated with lower survival than in men. We need to know whether this is because of patient-related factors and whether the lower survival is present in all subgroups of patients and for all time periods during which the surgery was performed. METHODS AND RESULTS: Using actuarial techniques, we determined the outcome of coronary bypass surgery performed for chronic stable and unstable angina in 1979 women and 6927 men. The operative mortality was 2.7% for women and 1.9% for men (P = .02). The higher operative mortality in women was seen in those with three-vessel disease or greater and abnormal left ventricular function (5.4% versus 2.8%, P = .009) and those with stable angina (2.6% versus 1.5%, P = .006). The 5-, 10-, 15-, and 18-year survival for women was 86 +/- 0.9%, 70 +/- 1.5%, 50 +/- 2.5%, and 37 +/- 6.4%, respectively, and for men, 88 +/- 0.4%, 73 +/- 0.7%, 54 +/- 1.2%, and 42 +/- 1.9%, respectively (P = .03). The lower survival in women compared with men was seen in those with three-vessel disease or greater and abnormal left ventricular function (at 10 years, 69 +/- 1.8% versus 73 +/- 0.8%, P = .005). At 15 years, the incidence of reoperation was 26 +/- 2.4% versus 28 +/- 1.2% and of myocardial infarction, 30 +/- 2.8% versus 32 +/- 1.3%, P = NS for either. The incidence of no angina or mild angina was 70% in women and 78% in men, P < .0001. The operative mortality and late survival of those operated on in different time periods for either women or men was not significantly different. Women were older (64 +/- 9.4 versus 61 +/- 9.9 years, P < .0001) and smaller (body surface area, 2.0 +/- 0.2 versus 1.7 +/- 0.2 m2, P < .0001), had a higher incidence of diabetes, systemic hypertension, and unstable angina, and had a smaller lumen of the left anterior descending coronary artery (1.7 +/- 0.4 versus 1.9 +/- 0.4 mm, P < .0001), right coronary artery, and diagonal arteries. More men were smokers, and men had a higher incidence of prior myocardial infarction, previous coronary bypass surgery, and extent of coronary disease and of abnormal left ventricular function. The Cox regression model of survival showed that independent risk factors for lower survival were older age, previous coronary bypass surgery, previous myocardial infarction, and diabetes. Sex was not an independent risk factor for poorer survival. CONCLUSIONS: Women have a higher operative mortality and lower long-term survival than men after coronary bypass surgery for angina. However, the differences are small, even if statistically significant. Importantly, patient-related factors and not sex are independent predictors of poorer survival. Therefore, coronary bypass surgery should not be delayed or denied to women who have the usual indications for surgery.

Actuarial Analysis↗
PubMed1993

Myocardial texture and cardiac calcification in uremia.

Seventy patients with advanced chronic renal failure were examined by 2D echocardiography in an effort to determine the prevalence of changes in myocardial texture and of valvular calcification. Changes in myocardial texture may be due to calcium deposition in the myocardium, the relationship between changes in myocardial texture and factors that may enhance myocardial calcification (blood levels of parathyroid hormone, PTH, and calcium-phosphorus product) were also evaluated. Myocardial texture was abnormal in 36 patients. In 68 patients, structural calcification could be assessed; a high degree of calcification was found. No correlation was found between either the echocardiographic parameter and blood levels of PTH or calcium-phosphorus product. We conclude that myocardial textural changes and intracardiac calcification are common in chronic renal failure and that these abnormalities do not correlate with blood PTH levels or calcium-phosphorus product.

Adult↗
PubMed1992

Hibernating myocardium: a historical perspective.

Hibernating myocardium refers to the presence of persistent myocardial and left ventricular dysfunction at rest, associated with conditions of severely reduced coronary blood flow. This left ventricular dysfunction probably represents an adaptive mechanism preventing irreversible myocardial cell damage, since myocardial and left ventricular dysfunction in hibernating myocardium improve following the restoration of coronary blood flow. This review examines the evolution of the concept of hibernation from a clinical observation of the potential underlying mechanisms recently proposed.

Adenosine Triphosphate↗
PubMed1992

Detection of acute myocardial infarction with digital image processing of two-dimensional echocardiograms.

We have previously described the ability of a computer-based image digitizing system to assess early textural changes in acute canine myocardial infarction. To determine whether this technique could be applied to human beings, we studied 12 patients with a first acute transmural myocardial infarction and five normal subjects. Two-dimensional echocardiograms were performed on days 1 and 8 in normal subjects and on days 1 (day of admission), 2, 3, 5, and 14 in the patient population. All recording parameters on the echocardiography machine were kept identical for serial studies. The mean period between hospitalization and first echocardiogram was 11.1 hours (range 4 to 20 hours). End-diastolic frames from the two-dimensional echocardiographic images were digitized and displayed on a monitor. The mean pixel intensity (MPI) (+/- SD) in the region of asynergy (area of myocardial infarction) and a normal area were determined. In normal volunteers, no significant change in MPI was noted between anteroseptal and lateral areas on two separate two-dimensional echocardiographic studies, which were performed 7 days apart (anteroseptal: MPI, 21.6 +/- 1.1 vs 21.8 +/- 0.4, p = not significant) and (lateral: MPI, 21.5 +/- 1.2 vs 21.4 +/- 1.4, p = not significant). In patients with myocardial infarction, a significant increase in MPI was noted on the first day of myocardial infarction between normal and infarcted myocardium (20.4 +/- 2.0 vs 24.3 +/- 2.3, p less than 0.05) and progressively increased thereafter until day 14 (20.5 +/- 1.7 vs 31.9 +/- 3.7, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗